The present invention relates generally to textile spinning or twisting machines or like apparatus and, more particularly, to a method and apparatus for use with such machines for the automatic simultaneous doffing from the machine spindles of tubes fully wound with yarn and the subsequent simultaneous donning of empty tubes onto the spindles.
As is known, textile spinning or twisting machines typically have a machine frame on which a plurality of spinning stations each having a tube-supporting spindle are longitudinally arranged. A transport arrangement may be provided to extend longitudinally along the machine frame for delivering empty tubes for donning onto the spindles and for removing fully wound tubes, often referred to as "bobbins," doffed from the spindles. A gripper beam may be provided in association with the transport arrangement for accomplishing the doffing and donning operation. Specifically, the gripper beam extends longitudinally along the machine frame and includes a plurality of gripper arrangements respectively associated with the plural spinning stations for gripping engagement of fully wound tubes and empty tubes for doffing and donning thereof. The gripper beam is selectively positionable at the spindles and at the transport arrangement and is operated by a control system for successively removing empty tubes from the transport arrangement, doffing fully wound tubes from the spindles, donning the empty tubes onto the spindles, and transferring the doffed tubes to the transport arrangement.
A representative doffing and donning apparatus and method of the above-described type is disclosed in West German Patentschrift No. 17 85 217, which discloses a textile spinning machine of the type having a plurality of adjacent spinning stations at each of which a roving is drawn through a drafting mechanism and subsequently spun as a yarn and wound onto a supporting tube driven by a machine spindle. Once the tubes at each spinning station have been fully wound with yarn to form bobbins, the bobbins are simultaneously doffed from all of the machine spindles and, thereafter, empty tubes are likewise donned simultaneously onto the spindles by a gripper beam of the aforementioned type having a plurality of gripper arrangements respectively associated with the plural spinning stations. In this apparatus and method, each gripper arrangement is provided with a pair of gripper assemblies disposed one behind the other in a plane essentially perpendicular to the longitudinal extent of the machine. A transport arrangement travels longitudinally along the machine beneath the spindles for delivering empty tubes for donning and removing doffed fully-wound bobbins. In order to replace a full bobbin with an empty tube, the gripper beam is positioned at the transport arrangement and the gripping assembly adjacently facing the machine frame in each gripper arrangement is operated to remove an empty tube from the transport arrangement. The gripper beam is then moved to a disposition at the spindles and the other free gripper assembly of each gripper arrangement engages and doffs the fully-wound bobbin from the respective spindle. As will be understood, during this procedure, the empty tube held by the first gripping assembly while awaiting donning is located between the doffed fully-wound bobbin and the machine frame. Next, the gripper beam is shifted perpendicularly to the longitudinal extent of the machine to position the empty tube over the spindle, whereupon the tube is donned onto the spindle. The gripper beam is then returned to the transport arrangement and the fully-wound bobbins doffed from the plural spindles are transferred to the transport arrangement.
Thus, the entire doffing and donning process as described is accomplished by essentially straight-line movements of the gripper beam transversely to the longitudinal extent of the machine. As will be understood, such movements require an extremely precise control of the drive mechanism for the gripper beam which necessarily is relatively expensive. Moreover, in the doffing and donning process as described, the spindles must be horizontally spaced from the machine frame a distance at least sufficient to enable the empty tubes to be moved between the spindles and the machine frame for donning.
Great Britain Patent No. 836,815 discloses another doffing and donning apparatus for spinning machines which similarly provides a plurality of gripper arrangements, each having a pair of gripper assemblies, respectively associated with the plural spinning stations of the machine. However, in this apparatus, each gripper arrangement is mounted for rotation about a horizontal axis for performing the doffing and donning operations. Necessarily, this rotatable mounting requires a considerable amount of space as well as a relatively expensive control mechanism. Additionally, to facilitate re-starting of the spindles following a doffing and donning operation, the yarn at each spinning station is wound onto a base area of the respective spindle before the spinning machine is stopped for the doffing and donning operation. A triangular stripping element is utilized at each spinning station to prevent the yarn from being clamped between the empty tube and the spindle when the empty tube is donned onto the spindle. Thus, the underwindings of the yarn permit the spinning machine to be automatically re-started after a doffing and donning operation. However, disadvantageously, individual yarn underwindings normally remain as waste on the bobbins, which underwindings usually must be removed by hand.